Check that there is no short in this circled location.? Also, this IC is a little skewed to the right, make sure all of its pins are nicely connected to the pads.
This is the most likely area of concern giving your symptoms. Good luck!
73
Bruce
KG8IW
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Hello all,
I have a 40m qcx+ and a qlg1, both working great together on wspr for several years now. Well, that until I went ahead and put my qlg1 in a new enclosure, on top of that I removed the 3mm LEDs (attached to the board) and replaced them with 5mm LEDs attached to longer wires so they would attach to the enclosure. On first test the qcx+ and qlg1 talk to each other fine, the qlg1 locked on satellites and all, but I noticed that the qcx was not outputting any power. The qcx+ transmits perfectly fine without the qlg1 attached. I obviously broke something, however I am not sure if I broke the qlg1 or the qcx, do you guys have any clues? Thanks
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?Don
If you would like to try signal tracing
Here is a? very nice PC soundcard oscilloscope for win XP and above
As you know surface mount components are packed tight
Be careful probing
I use a hat pin, small sharp point so not to skip off component es short to another,? plastic knob so personal contact does not introduce noise or 60 Hz junk
https://www.zeitnitz.eu/scope_en
It is also dual channel with a spectrum analyzer and sweep generator? And Free
72 73
John
N3AAZ
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Yes, but in the RF domain you need frequency and amplitude.? 73, Willie N1JBJ
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On Sep 2, 2023, at 11:28 AM, Da Amazin' man G0FTD via groups.io <punkbiscuit@...> wrote:
?On Sat, Sep 2, 2023 at 04:24 PM, Da Amazin' man G0FTD wrote:
In an analogue system? then ALL the tones of speech are present simultaneously.
Excepting xtal filter group delay params. That's why SSB always has that SSB sound, unless you're using a DC RX ;-) -- - 73 de Andy -
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Re: #QMX #BPF problems with fault finding
#qmx
#bpf
Voltage on C406 is 2.42V so I guess its correct. Just in case I will rewind T401 trifilar transformer in case there is a shortage inside winding.
---------------------------------
73 de Marek SP9TKW
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Hi John,
From research undertaken seems that WSPR on upper VHF bands for DX propagation is not very effective. Have found more than one study / paper that arrives at the same conclusion.
73
Nigel ZS6RN
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On Sat, Sep 2, 2023 at 04:24 PM, Da Amazin' man G0FTD wrote:
In an analogue system? then ALL the tones of speech are present simultaneously.
Excepting xtal filter group delay params. That's why SSB always has that SSB sound, unless you're using a DC RX ;-) -- - 73 de Andy -
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Surely this just amounts to creating? at any given point in time only one sampled frequency
and then switching to another fast enough in order to give the effect of two or more
simultaneous tones ?
In an analogue system? then ALL the tones of speech are present simultaneously.
--
- 73 de Andy -
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Well I have tried all the suggestions, quadruple checked the solder joints. There is NO sound other then the initial click at power up. It will work fine on Ft8. With FLdigi I can decode CW. The Device successfully Will transmit CW and decode CW both with the Key and on the air. Just nothing out of the head phone jack. I purchased another kit and am going to build it and then compare and contrast the two. If anyone has any other suggestions I'd love to try them.?
? Don..?
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Or for those of us in the U.S.:??
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On Sat, Sep 2, 2023 at 02:18 AM, Stephan Ahonen KE0WVA wrote:
What does the waveform of a two tone signal actually look like? The actual waveform, if you squint at it really hard, just looks like a single tone that's being amplitude modulated at the beat frequency between the two tones, and inverts polarity whenever the amplitude modulation has a zero crossing.
When I was writing my Teensy version of the uSDX I thought one day I would inject a perfect two tones programmatically and learn some things about the Si5351 frequency generation algorithms but much to my surprise the result was exactly as Stephan says but without any squinting.? Two tone testing the uSDX method of SSB is only a test of the AM modulator. I found that the SSB method is/was limited by the I2C bus speed and a more powerful processor does not gain you anywhere near as much improvement as one might expect.? It will be interesting to see what Hans can do as he seems like a very smart fellow. Ron? KE1MU
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On Sat, Sep 2, 2023 at 10:18 AM, Stephan Ahonen KE0WVA wrote:
An SSB signal, on the air, if you squint at it real hard, is just a single tone that changes frequency and amplitude very rapidly. You can reproduce this by doing the same thing, retuning an oscillator very rapidly and amplitude modulating it.
Fake news.
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Blew the PWR_HOLD port on the CPU
#qmx
So this was a totally self inflicted event, but I blew the PWR_HOLD port on the CPU. I don't particularly like the flex the left part of the control board has when pressing on the left encoder so was experimenting with different materials between the encoder and the 5v SMPS connector.
Symptoms afterwards were QMX would power on but as soon as the left encoder was released it would power off immediately. Initially I thought the PWR_HOLD port or PWM_5V port or both were blown. Narrowed it down to the PWR_HOLD port only. Hmmm, can I fix this. First thought was to simply change which port PWR_HOLD is utilizing but alas no access to firmware. What else to do? Only restriction was that I wanted changes only to the main board and not the SMPSs as they were fine. So I decided to cut the PWR_HOLD 90 degree angle pin which would severe the PWR_HOLD port from the 5v SMPS. Then run Vdd to the upper part of the severed connection so that PWR_HOLD on the SMPS was always at Vdd. I picked Vdd off C429 and ran the line under the 5v power board connectors. Works perfect. Well almost. Now when powering off I have to actually remove power after I see the "Shutdown" message. Fortunately my battery supply has a switch so this is no problem. Every thing else works perfect. May still add a 100k resistor from the port (bottom of the cut pin) to ground - not sure it's necessary though. This rig will remain my personal rig and not be sold.
Lesson for today: Be careful out there, especially when probing a powered rig.
As a side note you can see that I don't try to lay the LPF toroids flat. There is room to angle them and it makes any adjustments easier.
-mike/w1mt
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Andre, quite simply because GPT4 is beyond awesome and could be of great assistance in programming SDR Transceivers like the QMX
but nobody seems to have understood it's capabilities which is a pity.
Paul DJ0CU G4ADF
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Useful for probing short timescale propagation. WSPR needs 2 min, FT8 15 sec.? Sporadic-E often fades very quickly :-(? Tropo is more likely to support WSPR.
FT4 as well !?? (might also catch some meteor-scatter, aircraft-scatter)
Multi-mode beacons are more efficient as they can reveal differing propagation conditions.?
Sometimes WSPR is "better" than FT8, sometimes "worse", depending on the timescales involved in the propagation mode.
The more beacon-ing modes, the better :-)? Regards,? Ed? G8BQR
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On Fri, Sep 1, 2023 at 11:31 PM, Shirley Dulcey KE1L wrote:
The STM32F446 microcontroller has two 12 bit DACs. A DAC output is used to control the amplitude of the transmitter output; it's not done with PWM. The current firmware only uses that to control the rise and fall times of CW transmissions.
If Q507 is being driven linearly then I hope it has good heat sinking. I would have thought that in order to keep the efficiency benefits if class E you'd want to switch the uc pin driving that transistor from an analog DAC mode to a pwm mode.
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Re: QMX Display Brightness
Without knowing your lighting conditions no one can say. ? Certainly the base designs run the backlight as ‘hot’ as possible and possibly above the backlight LED ratings in some sets/supply voltages ?
It’s possible to add resistance up to 3-10 times the original value for less brightness / dark room indoor use. ??
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On Sat, Sep 2, 2023 at 12:08 AM, Colin Kaminski wrote:
I may have a simplistic view, and I hope to be corrected, but it seems to me that an EER method can only reproduce a single tone at a time
This is sort of the equivalent of saying "but a DAC can only produce one voltage at a time, how can you reproduce an entire waveform that way?"
The magic happens when you do it many thousands of times a second.
What does the waveform of a two tone signal actually look like? The actual waveform, if you squint at it really hard, just looks like a single tone that's being amplitude modulated at the beat frequency between the two tones, and inverts polarity whenever the amplitude modulation has a zero crossing.
An SSB signal, on the air, if you squint at it real hard, is just a single tone that changes frequency and amplitude very rapidly. You can reproduce this by doing the same thing, retuning an oscillator very rapidly and amplitude modulating it.
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Re: #QMX FT8 Signal to noise remarkably good.
#qmx
My totally uninformed guess is that it might come down to being an advantage of the Tayloe mixer used in the QMX over the RF sampling ADC used in the 7300.
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Re: #QMX FT8 Signal to noise remarkably good.
#qmx
On 02/09/2023 07:40, Chris wrote: The 7300 gave the S/N as -16 to -18.? Ran both at once in Rx and it was consistent, QMX -3 to -5, 7300 -17.? Similar antennas (EFHW and doublet side by side). Chris, Maybe the QMX is simply better. But I would carry out an extended test simultaneously on one antenna with a splitter. I've done that many times using WSPR. Even then I find results are not conclusive. When I try on different antennas it can get even more confusing. 73 Alan G4ZFQ
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Marek SP9TKW
Donald Gover
Mike Besemer - WM4B
Tronald Dump
Bruce Akhurst